GALNT3 encodes UDP-GalNAc transferase 3, a member of the GalNAc-transferases family. This family transfers an N-acetyl galactosamine to the hydroxyl group of a serine or threonine residue in the first step of O-linked oligosaccharide biosynthesis. Individual GalNAc-transferases have distinct activities and initiation of O-glycosylation is regulated by a repertoire of GalNAc-transferases. The protein is highly homologous to other family members, however the enzymes have different substrate specificities.Synonyms: GalNAc transferase 3, GalNAc-T3, Polypeptide N-acetylgalactosaminyltransferase 3, Protein-UDP acetylgalactosaminyltransferase 3, UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 3, pp-GaNTase 3